Don't emit binding pattern pattern / optional parameter error when an initializer is present (#52880)

Author: jakebailey

src/compiler/checker.ts

@@ -37648,7 +37648,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 error(node.name, Diagnostics.constructor_cannot_be_used_as_a_parameter_property_name);
             }
         }
-        if ((node.questionToken || isJSDocOptionalParameter(node)) && isBindingPattern(node.name) && (func as FunctionLikeDeclaration).body) {
+        if (!node.initializer && isOptionalDeclaration(node) && isBindingPattern(node.name) && (func as FunctionLikeDeclaration).body) {
             error(node, Diagnostics.A_binding_pattern_parameter_cannot_be_optional_in_an_implementation_signature);
         }
         if (node.name && isIdentifier(node.name) && (node.name.escapedText === "this" || node.name.escapedText === "new")) {

tests/baselines/reference/optionalBindingParameters4.symbols

@@ -0,0 +1,12 @@
+=== /a.js ===
+/** 
+* @param {{ cause?: string }} [options] 
+*/ 
+function foo({ cause } = {}) {
+>foo : Symbol(foo, Decl(a.js, 0, 0))
+>cause : Symbol(cause, Decl(a.js, 3, 14))
+
+    return cause;
+>cause : Symbol(cause, Decl(a.js, 3, 14))
+}
+

tests/baselines/reference/optionalBindingParameters4.types

@@ -0,0 +1,13 @@
+=== /a.js ===
+/** 
+* @param {{ cause?: string }} [options] 
+*/ 
+function foo({ cause } = {}) {
+>foo : ({ cause }?: {    cause?: string;}) => string
+>cause : string
+>{} : {}
+
+    return cause;
+>cause : string
+}
+

tests/cases/conformance/es6/destructuring/optionalBindingParameters4.ts

@@ -0,0 +1,11 @@
+// @checkJs: true
+// @allowJs: true
+// @noEmit: true
+// @filename: /a.js
+
+/** 
+* @param {{ cause?: string }} [options] 
+*/ 
+function foo({ cause } = {}) {
+    return cause;
+}