patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI

Problem:  Vim9: hard to debug vim9_class errors from CI
Solution: Include the line number in assert_xxx() calls.  Include the
          entire error message in the tests.  Fix the indentation in the
          test file.  Add tags for new error codes.

closes: #13206

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

runtime/doc/tags

@@ -4479,6 +4479,9 @@ E1380	vim9class.txt	/*E1380*
 E1381	vim9class.txt	/*E1381*
 E1382	vim9class.txt	/*E1382*
 E1383	vim9class.txt	/*E1383*
+E1384	vim9class.txt	/*E1384*
+E1385	vim9class.txt	/*E1385*
+E1386	vim9class.txt	/*E1386*
 E1387	vim9class.txt	/*E1387*
 E1388	vim9class.txt	/*E1388*
 E1389	vim9class.txt	/*E1389*

runtime/doc/vim9class.txt

@@ -258,10 +258,15 @@ If the class extends a parent class, the same thing happens.  In the second
 step the object variables of the parent class are initialized first.  There is
 no need to call "super()" or "new()" on the parent.
 
-						*E1365*
+							*E1365*
 When defining the new() method the return type should not be specified.  It
 always returns an object of the class.
 
+							*E1386*
+When invoking an object method, the method name should be preceded by the
+object variable name.  A object method cannot be invoked using the class
+name.
+
 ==============================================================================
 
 3.  Class Variables and Methods			*Vim9-class-member*
@@ -282,7 +287,7 @@ prefix in the class where they are defined: >
 Since the name is used as-is, shadowing the name by a method argument name
 or local variable name is not allowed.
 
-							*E1374* *E1375*
+					    *E1374* *E1375* *E1384* *E1385*
 To access a class member outside of the class where it is defined, the class
 name prefix must be used.  A class member cannot be accessed using an object.
 

src/errors.h

@@ -2396,6 +2396,7 @@ EXTERN char e_io_file_requires_name_to_be_set[]
 #ifdef FEAT_EVAL
 EXTERN char e_invalid_callback_argument[]
 	INIT(= N_("E921: Invalid callback argument"));
+// E922 unused
 EXTERN char e_second_argument_of_function_must_be_list_or_dict[]
 	INIT(= N_("E923: Second argument of function() must be a list or a dict"));
 #endif
@@ -2790,7 +2791,7 @@ EXTERN char e_no_white_space_allowed_after_dot[]
 	INIT(= N_("E1074: No white space allowed after dot"));
 EXTERN char e_namespace_not_supported_str[]
 	INIT(= N_("E1075: Namespace not supported: %s"));
-// E1076 was deleted
+// E1076 unused (was deleted)
 EXTERN char e_missing_argument_type_for_str[]
 	INIT(= N_("E1077: Missing argument type for %s"));
 #endif
@@ -2858,6 +2859,7 @@ PLURAL_MSG(e_one_argument_too_many, "E1106: One argument too many",
 
 EXTERN char e_string_list_dict_or_blob_required[]
 	INIT(= N_("E1107: String, List, Dict or Blob required"));
+// E1108 unused
 EXTERN char e_list_item_nr_is_not_list[]
 	INIT(= N_("E1109: List item %d is not a List"));
 EXTERN char e_list_item_nr_does_not_contain_3_numbers[]
@@ -3210,6 +3212,7 @@ EXTERN char e_list_dict_blob_or_string_required_for_argument_nr[]
 	INIT(= N_("E1251: List, Dictionary, Blob or String required for argument %d"));
 EXTERN char e_string_list_or_blob_required_for_argument_nr[]
 	INIT(= N_("E1252: String, List or Blob required for argument %d"));
+// E1253 unused
 EXTERN char e_cannot_use_script_variable_in_for_loop[]
 	INIT(= N_("E1254: Cannot use script variable in for loop"));
 #endif
@@ -3523,7 +3526,7 @@ EXTERN char e_class_method_str_accessible_only_using_class_str[]
 	INIT(= N_("E1385: Class method \"%s\" accessible only using class \"%s\""));
 EXTERN char e_object_method_str_accessible_only_using_object_str[]
 	INIT(= N_("E1386: Object method \"%s\" accessible only using class \"%s\" object"));
-EXTERN char e_public_member_not_supported_in_interface[]
+EXTERN char e_public_variable_not_supported_in_interface[]
 	INIT(= N_("E1387: Public variable not supported in an interface"));
 EXTERN char e_public_keyword_not_supported_for_method[]
 	INIT(= N_("E1388: Public keyword not supported for a method"));