diff --git a/src/Psalm/Checker/FunctionChecker.php b/src/Psalm/Checker/FunctionChecker.php
index 15b3df377..ad24dae35 100644
--- a/src/Psalm/Checker/FunctionChecker.php
+++ b/src/Psalm/Checker/FunctionChecker.php
@@ -494,7 +494,7 @@ class FunctionChecker extends FunctionLikeChecker
                             }
                         } elseif ($first_arg->inferredType->hasScalarType() &&
                             ($second_arg = $call_args[1]->value) &&
-                            $second_arg->inferredType &&
+                            isset($second_arg->inferredType) &&
                             $second_arg->inferredType->hasScalarType()
                         ) {
                             return Type::combineUnionTypes($first_arg->inferredType, $second_arg->inferredType);
diff --git a/src/Psalm/Checker/MethodChecker.php b/src/Psalm/Checker/MethodChecker.php
index 41a0e520e..757a0bf30 100644
--- a/src/Psalm/Checker/MethodChecker.php
+++ b/src/Psalm/Checker/MethodChecker.php
@@ -504,7 +504,9 @@ class MethodChecker extends FunctionLikeChecker
 
         $old_method_id = null;
 
-        ClassLikeChecker::registerClass($method_parts[0]);
+        if (ClassLikeChecker::registerClass($method_parts[0]) === false) {
+            return false;
+        }
 
         $class_storage = ClassLikeChecker::$storage[$method_parts[0]];
 
diff --git a/src/Psalm/Checker/Statements/Expression/AssignmentChecker.php b/src/Psalm/Checker/Statements/Expression/AssignmentChecker.php
index 1392fa7be..d8f246916 100644
--- a/src/Psalm/Checker/Statements/Expression/AssignmentChecker.php
+++ b/src/Psalm/Checker/Statements/Expression/AssignmentChecker.php
@@ -422,7 +422,7 @@ class AssignmentChecker
                     continue;
                 }
 
-                if (MethodChecker::methodExists($lhs_type_part . '::__set')) {
+                if (!$lhs_type_part->isObject() && MethodChecker::methodExists($lhs_type_part . '::__set')) {
                     $context->vars_in_scope[$var_id] = Type::getMixed();
                     continue;
                 }
diff --git a/src/Psalm/Checker/TraitChecker.php b/src/Psalm/Checker/TraitChecker.php
index bc43ad529..bfd66a6f8 100644
--- a/src/Psalm/Checker/TraitChecker.php
+++ b/src/Psalm/Checker/TraitChecker.php
@@ -123,7 +123,10 @@ class TraitChecker extends ClassLikeChecker
             return self::$existing_traits[strtolower($trait_name)];
         }
 
+        $old_level = error_reporting();
+        error_reporting(0);
         $trait_exists = trait_exists($trait_name);
+        error_reporting($old_level);
 
         self::$existing_traits[strtolower($trait_name)] = $trait_exists;
 
diff --git a/src/Psalm/Checker/TypeChecker.php b/src/Psalm/Checker/TypeChecker.php
index dcd95f19a..b2b45b2e1 100644
--- a/src/Psalm/Checker/TypeChecker.php
+++ b/src/Psalm/Checker/TypeChecker.php
@@ -757,7 +757,7 @@ class TypeChecker
                     $type_match_found = true;
                 }
 
-                if ($container_type_part->isString() && $input_type_part->isObjectType()) {
+                if ($container_type_part->isString() && $input_type_part->isObjectType() && !$input_type_part->isObject()) {
                     // check whether the object has a __toString method
                     if (MethodChecker::methodExists($input_type_part->value . '::__toString')) {
                         $type_match_found = true;
diff --git a/src/Psalm/Type/Atomic.php b/src/Psalm/Type/Atomic.php
index ef7927d69..816036132 100644
--- a/src/Psalm/Type/Atomic.php
+++ b/src/Psalm/Type/Atomic.php
@@ -58,7 +58,7 @@ class Atomic extends Type
         if (isset($aliased_classes[strtolower($this->value)])) {
             return $aliased_classes[strtolower($this->value)];
         }
-        
+
         return '\\' . $this->value;
     }
 
@@ -182,6 +182,7 @@ class Atomic extends Type
                     && !$this->isEmpty()
                     && !$this->isResource()
                     && !$this->isIterable()
+                    && !$this->isScalar()
                 );
     }