fix check order of strictNullChecks and noImplicitReturns

Author: Kingwl

src/compiler/checker.ts

@@ -22054,6 +22054,10 @@ namespace ts {
             if (func) {
                 const signature = getSignatureFromDeclaration(func);
                 const returnType = getReturnTypeOfSignature(signature);
+                if (func.kind !== SyntaxKind.Constructor && compilerOptions.noImplicitReturns && !isUnwrappedReturnTypeVoidOrAny(func, returnType)) {
+                    // The function has a return type, but the return statement doesn't have an expression.
+                    error(node, Diagnostics.Not_all_code_paths_return_a_value);
+                }
                 if (strictNullChecks || node.expression || returnType.flags & TypeFlags.Never) {
                     const exprType = node.expression ? checkExpressionCached(node.expression) : undefinedType;
                     const functionFlags = getFunctionFlags(func);
@@ -22091,10 +22095,6 @@ namespace ts {
                         }
                     }
                 }
-                else if (func.kind !== SyntaxKind.Constructor && compilerOptions.noImplicitReturns && !isUnwrappedReturnTypeVoidOrAny(func, returnType)) {
-                    // The function has a return type, but the return statement doesn't have an expression.
-                    error(node, Diagnostics.Not_all_code_paths_return_a_value);
-                }
             }
         }
 

tests/baselines/reference/generatorStrictNullChecks.errors.txt

@@ -0,0 +1,13 @@
+tests/cases/conformance/es6/yieldExpressions/generatorStrictNullChecks.ts(3,9): error TS7030: Not all code paths return a value.
+
+
+==== tests/cases/conformance/es6/yieldExpressions/generatorStrictNullChecks.ts (1 errors) ====
+    function* testGenerator () {
+        if (Math.random() > 0.5) {
+            return;
+            ~~~~~~~
+!!! error TS7030: Not all code paths return a value.
+        }
+        yield 'hello';
+    }
+    

tests/baselines/reference/generatorStrictNullChecks.js

@@ -0,0 +1,16 @@
+//// [generatorStrictNullChecks.ts]
+function* testGenerator () {
+    if (Math.random() > 0.5) {
+        return;
+    }
+    yield 'hello';
+}
+
+
+//// [generatorStrictNullChecks.js]
+function* testGenerator() {
+    if (Math.random() > 0.5) {
+        return;
+    }
+    yield 'hello';
+}

tests/baselines/reference/generatorStrictNullChecks.symbols

@@ -0,0 +1,14 @@
+=== tests/cases/conformance/es6/yieldExpressions/generatorStrictNullChecks.ts ===
+function* testGenerator () {
+>testGenerator : Symbol(testGenerator, Decl(generatorStrictNullChecks.ts, 0, 0))
+
+    if (Math.random() > 0.5) {
+>Math.random : Symbol(Math.random, Decl(lib.es5.d.ts, --, --))
+>Math : Symbol(Math, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
+>random : Symbol(Math.random, Decl(lib.es5.d.ts, --, --))
+
+        return;
+    }
+    yield 'hello';
+}
+

tests/baselines/reference/generatorStrictNullChecks.types

@@ -0,0 +1,19 @@
+=== tests/cases/conformance/es6/yieldExpressions/generatorStrictNullChecks.ts ===
+function* testGenerator () {
+>testGenerator : () => IterableIterator<string>
+
+    if (Math.random() > 0.5) {
+>Math.random() > 0.5 : boolean
+>Math.random() : number
+>Math.random : () => number
+>Math : Math
+>random : () => number
+>0.5 : 0.5
+
+        return;
+    }
+    yield 'hello';
+>yield 'hello' : any
+>'hello' : "hello"
+}
+

tests/cases/conformance/es6/yieldExpressions/generatorStrictNullChecks.ts

@@ -0,0 +1,10 @@
+// @target: esnext
+// @noImplicitReturns: true
+// @strictNullChecks: true
+
+function* testGenerator () {
+    if (Math.random() > 0.5) {
+        return;
+    }
+    yield 'hello';
+}