diff --git a/src/Psalm/Checker/ClassLikeChecker.php b/src/Psalm/Checker/ClassLikeChecker.php
index d2f6d30e4..67a087125 100644
--- a/src/Psalm/Checker/ClassLikeChecker.php
+++ b/src/Psalm/Checker/ClassLikeChecker.php
@@ -65,7 +65,7 @@ abstract class ClassLikeChecker implements StatementsSource
     /**
      * The parent class
      *
-     * @var string
+     * @var string|null
      */
     protected $parent_class;
 
diff --git a/src/Psalm/Checker/FunctionLikeChecker.php b/src/Psalm/Checker/FunctionLikeChecker.php
index a7eb49359..de5d72074 100644
--- a/src/Psalm/Checker/FunctionLikeChecker.php
+++ b/src/Psalm/Checker/FunctionLikeChecker.php
@@ -55,6 +55,8 @@ abstract class FunctionLikeChecker implements StatementsSource
 
             $statements_checker = new StatementsChecker($this, $has_context, $check_methods);
 
+            $hash = null;
+
             if ($this instanceof MethodChecker) {
                 if (ClassLikeChecker::getThisClass()) {
                     $hash = $this->getMethodId() . json_encode([$context->vars_in_scope, $context->vars_possibly_in_scope]);
@@ -87,6 +89,8 @@ abstract class FunctionLikeChecker implements StatementsSource
                     $param_type = null;
 
                     if ($param->type) {
+                        $param_type_string = '';
+
                         if (is_string($param->type)) {
                             $param_type_string = $param->type;
                         }
@@ -167,7 +171,7 @@ abstract class FunctionLikeChecker implements StatementsSource
                 }
             }
 
-            if (ClassLikeChecker::getThisClass() && $this instanceof MethodChecker) {
+            if ($hash && ClassLikeChecker::getThisClass() && $this instanceof MethodChecker) {
                 self::$no_effects_hashes[$hash] = [$context->vars_in_scope, $context->vars_possibly_in_scope];
             }
         }
diff --git a/src/Psalm/Checker/TypeChecker.php b/src/Psalm/Checker/TypeChecker.php
index 154483f0c..e7d03f875 100644
--- a/src/Psalm/Checker/TypeChecker.php
+++ b/src/Psalm/Checker/TypeChecker.php
@@ -922,8 +922,8 @@ class TypeChecker
     /**
      * Takes two arrays of types and merges them
      *
-     * @param  array<UnionType>  $new_types
-     * @param  array<UnionType>  $existing_types
+     * @param  array<Type\Union>  $new_types
+     * @param  array<Type\Union>  $existing_types
      * @return array
      */
     public static function combineKeyedTypes(array $new_types, array $existing_types)
@@ -1079,7 +1079,7 @@ class TypeChecker
                 continue;
             }
 
-            if (!($inferred_atomic_type instanceof Type\Generic) && $declared_atomic_type instanceof Type\Generic) {
+            if (!($inferred_atomic_type instanceof Type\Generic)) {
                 // @todo handle this better
                 continue;
             }
diff --git a/src/Psalm/Config.php b/src/Psalm/Config.php
index 0eab91a15..fc7ebc3fa 100644
--- a/src/Psalm/Config.php
+++ b/src/Psalm/Config.php
@@ -58,7 +58,7 @@ class Config
     protected $filetype_handlers = [];
 
     /**
-     * @var array<string, FileFilter>
+     * @var array<string,FileFilter>
      */
     protected $issue_handlers = [];
 
diff --git a/src/Psalm/Context.php b/src/Psalm/Context.php
index 060549cd0..115fe7641 100644
--- a/src/Psalm/Context.php
+++ b/src/Psalm/Context.php
@@ -7,9 +7,10 @@ use Psalm\Checker\StatementsChecker;
 
 class Context
 {
-    /** @var array<string, Type\Union> */
+    /** @var array<string,Type\Union> */
     public $vars_in_scope = [];
 
+    /** @var array<string,bool> */
     public $vars_possibly_in_scope = [];
 
     /** @var boolean */
diff --git a/src/Psalm/Type.php b/src/Psalm/Type.php
index dd7a1c213..ceb1256d8 100644
--- a/src/Psalm/Type.php
+++ b/src/Psalm/Type.php
@@ -134,7 +134,7 @@ abstract class Type
     }
 
     /**
-     * @return array<int, string>
+     * @return array<int,string>
      */
     public static function tokenize($return_type)
     {
@@ -411,6 +411,8 @@ abstract class Type
         }
 
         $key_types = [];
+
+        /** @var array<string,array<string,Union>> */
         $value_types = [];
 
         foreach ($types as $type) {
diff --git a/src/Psalm/Type/Generic.php b/src/Psalm/Type/Generic.php
index 89adbdd67..4e58fe096 100644
--- a/src/Psalm/Type/Generic.php
+++ b/src/Psalm/Type/Generic.php
@@ -12,7 +12,7 @@ class Generic extends Atomic
     /**
      * Constructs a new instance of a generic type
      * @param string            $value
-     * @param array<Type\Union> $type_params
+     * @param array<int,Union>  $type_params
      */
     public function __construct($value, array $type_params)
     {
diff --git a/src/Psalm/Type/GenericArray.php b/src/Psalm/Type/GenericArray.php
index de8675fd1..09c7c177a 100644
--- a/src/Psalm/Type/GenericArray.php
+++ b/src/Psalm/Type/GenericArray.php
@@ -11,7 +11,7 @@ class GenericArray extends Generic
     /**
      * Constructs a new instance of a generic type
      * @param string            $value
-     * @param array<Type\Union> $type_params
+     * @param array<int,Union> $type_params
      */
     public function __construct($value, array $type_params)
     {
diff --git a/src/Psalm/Type/ObjectLike.php b/src/Psalm/Type/ObjectLike.php
index 8e43ebdc1..a17c15129 100644
--- a/src/Psalm/Type/ObjectLike.php
+++ b/src/Psalm/Type/ObjectLike.php
@@ -8,13 +8,13 @@ class ObjectLike extends Atomic
 {
     public $value = 'object-like';
 
-    /** @var array<string,Type\Union> */
+    /** @var array<string,Union> */
     public $properties;
 
     /**
      * Constructs a new instance of a generic type
      * @param string            $value
-     * @param array<string,Type\Union> $type_params
+     * @param array<string,Union> $type_params
      */
     public function __construct($value, array $properties)
     {
diff --git a/src/Psalm/Type/ParseTree.php b/src/Psalm/Type/ParseTree.php
index bb94cdeb2..9e2989a24 100644
--- a/src/Psalm/Type/ParseTree.php
+++ b/src/Psalm/Type/ParseTree.php
@@ -10,7 +10,7 @@ class ParseTree
     const UNION = '|';
 
     /** @var array<ParseTree> */
-    public $children;
+    public $children = [];
 
     /** @var string|null */
     public $value;
@@ -26,7 +26,6 @@ class ParseTree
     {
         $this->value = $value;
         $this->parent = $parent;
-        $this->children = [];
     }
 
     /**
@@ -123,6 +122,10 @@ class ParseTree
                         continue;
                     }
 
+                    if (!$current_parent) {
+                        throw new \InvalidArgumentException('Cannot process colon without parent');
+                    }
+
                     $new_parent_leaf = new self(self::OBJECT_PROPERTY, $current_parent);
                     $new_parent_leaf->children = [$current_leaf];
                     $current_leaf->parent = $new_parent_leaf;
diff --git a/src/Psalm/Type/Union.php b/src/Psalm/Type/Union.php
index c37c78afb..f926ca63a 100644
--- a/src/Psalm/Type/Union.php
+++ b/src/Psalm/Type/Union.php
@@ -8,12 +8,12 @@ use Psalm\Checker\ClassChecker;
 
 class Union extends Type
 {
-    /** @var array<string, Atomic> */
+    /** @var array<string,Atomic> */
     public $types = [];
 
     /**
      * Constructs an Union instance
-     * @param array<int, AtomicType>     $types
+     * @param array<int,Atomic>     $types
      */
     public function __construct(array $types)
     {