feat: error if call receiver is class without constructor

src/language/validation/types.ts

@@ -1,7 +1,7 @@
 import { getContainerOfType, ValidationAcceptor } from 'langium';
 import {
     isSdsAnnotation,
-    isSdsCallable,
+    isSdsCallable, isSdsClass,
     isSdsLambda, isSdsMemberAccess, isSdsPipeline, isSdsReference, isSdsSchema,
     SdsAttribute,
     SdsCall,
@@ -46,6 +46,11 @@ export const callReceiverMustBeCallable = (services: SafeDsServices) => {
                 node: node.receiver,
                 code: CODE_TYPE_CALLABLE_RECEIVER,
             });
+        } else if (isSdsClass(callable) && !callable.parameterList) {
+            accept('error', "Cannot instantiate a class that has no constructor.", {
+                node: node.receiver,
+                code: CODE_TYPE_CALLABLE_RECEIVER,
+            });
         }
     };
 };

tests/resources/validation/types/checking/called class must have constructor/main.sdstest

@@ -0,0 +1,14 @@
+package tests.validation.types.checking.calledClassMustHaveConstructor
+
+class A
+
+class B()
+
+pipeline test {
+
+    // $TEST$ error "Cannot instantiate a class that has no constructor."
+    val a = »A«();
+
+    // $TEST$ no error "Cannot instantiate a class that has no constructor."
+    val b = »B«();
+}