Bug 1462326 - Add missing null check when calling shell's module resolve hook r=luke

js/src/jit-test/tests/modules/bug-1462326.js

@@ -0,0 +1,6 @@
+// |jit-test| error: Error
+
+let m = parseModule(`
+  import A from "A";
+`);
+m.declarationInstantiation();

js/src/shell/js.cpp

@@ -4293,6 +4293,10 @@ static JSObject*
 CallModuleResolveHook(JSContext* cx, HandleObject module, HandleString specifier)
 {
     ShellContext* sc = GetShellContext(cx);
+    if (!sc->moduleResolveHook) {
+        JS_ReportErrorASCII(cx, "Module resolve hook not set");
+        return nullptr;
+    }
 
     JS::AutoValueArray<2> args(cx);
     args[0].setObject(*module);