Fix #5020 - remove previous catch var assertions when assigning inside catch

src/Psalm/Context.php

@@ -630,6 +630,10 @@ class Context
         }
     }
 
+    /**
+     * This method is used after assignments to variables to remove any existing
+     * items in $vars_in_scope that are now made redundant by an update to some data
+     */
     public function removeDescendents(
         string $remove_var_id,
         ?Union $existing_type = null,

src/Psalm/Internal/Analyzer/Statements/Block/TryAnalyzer.php

@@ -306,6 +306,14 @@ class TryAnalyzer
                     )
                 );
 
+                // removes dependent vars from $context
+                $catch_context->removeDescendents(
+                    $catch_var_id,
+                    null,
+                    $catch_context->vars_in_scope[$catch_var_id],
+                    $statements_analyzer
+                );
+
                 $catch_context->vars_possibly_in_scope[$catch_var_id] = true;
 
                 $location = new CodeLocation($statements_analyzer->getSource(), $catch->var);

tests/Template/FunctionTemplateAssertTest.php

@@ -732,6 +732,41 @@ class FunctionTemplateAssertTest extends TestCase
                         }
                     }'
             ],
+            'assertSameOnMemoizedMethodCall' => [
+                '<?php
+                    function testValidUsername(): void {
+                        try {
+                            validateUsername("123");
+                            throw new Exception("Failed to throw exception for short username");
+                        } catch (Exception $e) {
+                            assertSame("a", $e->getMessage());
+                        }
+
+                        try {
+                            validateUsername("invalid#1");
+                        } catch (Exception $e) {
+                            assertSame("b", $e->getMessage());
+                        }
+                    }
+
+                    /**
+                     * @psalm-template ExpectedType
+                     * @psalm-param ExpectedType $expected
+                     * @psalm-param mixed $actual
+                     * @psalm-assert =ExpectedType $actual
+                     */
+                    function assertSame($expected, $actual): void {
+                        if ($actual !== $expected) {
+                            throw new Exception("Bad");
+                        }
+                    }
+
+                    function validateUsername(string $username): void {
+                        if (strlen($username) < 5) {
+                            throw new Exception("Username must be at least 5 characters long");
+                        }
+                    }'
+            ],
         ];
     }