FIX: Better error reporting for copy calls

src/build/compile_test.rs

@@ -507,3 +507,25 @@ fn test_let_missing_semicolon_compile_failure() {
         ],
     )
 }
+
+#[test]
+fn test_copy_expression_not_a_tuple_compile_failure() {
+    assert_build_failure(
+        "let foo = 1;\nfoo{};",
+        vec![
+            Regex::new(r"Expected Tuple or Module but got \(1\)").unwrap(),
+            Regex::new(r"at <eval> line: 2, column: 1").unwrap(),
+        ],
+    )
+}
+
+#[test]
+fn test_copy_expression_wrong_field_type_compile_failure() {
+    assert_build_failure(
+        "let foo = {bar=1};\nfoo{bar=[]};",
+        vec![
+            Regex::new(r"Expected type Integer for field bar but got \(List\)").unwrap(),
+            Regex::new(r"at <eval> line: 2, column: 5").unwrap(),
+        ],
+    )
+}

src/build/mod.rs

@@ -1042,7 +1042,7 @@ impl<'a> FileBuilder<'a> {
                     } else {
                         return Err(Box::new(error::BuildError::new(
                             format!(
-                                "Expected type {} for field {} but got {}",
+                                "Expected type {} for field {} but got ({})",
                                 src_val.1.type_name(),
                                 key.fragment,
                                 expr_result.type_name()
@@ -1130,7 +1130,7 @@ impl<'a> FileBuilder<'a> {
             }
         }
         Err(Box::new(error::BuildError::new(
-            format!("Expected Tuple or Module got {}", v),
+            format!("Expected Tuple or Module but got ({})", v),
             error::ErrorType::TypeFail,
             def.selector.pos().clone(),
         )))