Parser: improved message when a module cannot be loaded.

This is less confusing because it covers more cases, including when
there are not enough file access rights.

Author: xeioex

src/njs_module.c

@@ -148,7 +148,7 @@ njs_module_require(njs_vm_t *vm, njs_value_t *args, njs_uint_t nargs,
 
     module = njs_module_find(vm, &name, 0);
     if (njs_slow_path(module == NULL)) {
-        njs_error(vm, "Cannot find module \"%V\"", &name);
+        njs_error(vm, "Cannot load module \"%V\"", &name);
 
         return NJS_ERROR;
     }

src/njs_parser.c

@@ -8114,7 +8114,7 @@ njs_parser_module(njs_parser_t *parser, njs_str_t *name)
     vm = parser->vm;
 
     if (name->length == 0) {
-        njs_parser_syntax_error(parser, "Cannot find module \"%V\"", name);
+        njs_parser_syntax_error(parser, "Cannot load module \"%V\"", name);
         return NULL;
     }
 
@@ -8124,13 +8124,14 @@ njs_parser_module(njs_parser_t *parser, njs_str_t *name)
     }
 
     if (vm->module_loader == NULL) {
-        njs_parser_syntax_error(parser, "Cannot load module \"%V\"", name);
+        njs_parser_syntax_error(parser,
+                                "Module loader callback is not provided");
         return NULL;
     }
 
     module = vm->module_loader(vm, vm->module_loader_opaque, name);
     if (module == NULL) {
-        njs_parser_syntax_error(parser, "Cannot find module \"%V\"", name);
+        njs_parser_syntax_error(parser, "Cannot load module \"%V\"", name);
         return NULL;
     }
 

src/test/njs_unit_test.c

@@ -18975,7 +18975,7 @@ static njs_unit_test_t  njs_test[] =
     /* require(). */
 
     { njs_str("require('unknown_module')"),
-      njs_str("Error: Cannot find module \"unknown_module\"") },
+      njs_str("Error: Cannot load module \"unknown_module\"") },
 
     { njs_str("require()"),
       njs_str("TypeError: missing path") },
@@ -19045,7 +19045,7 @@ static njs_unit_test_t  njs_test[] =
       njs_str("SyntaxError: Unexpected token \"{\" in 1") },
 
     { njs_str("import x from ''"),
-      njs_str("SyntaxError: Cannot find module \"\" in 1") },
+      njs_str("SyntaxError: Cannot load module \"\" in 1") },
 
     { njs_str("export"),
       njs_str("SyntaxError: Illegal export statement in 1") },

test/shell_test_njs.exp

@@ -173,13 +173,13 @@ njs_test {
 # quiet mode
 
 njs_run {"-q" "test/js/import_chain.t.js"} \
-        "SyntaxError: Cannot find module \"lib2.js\" in 7"
+        "SyntaxError: Cannot load module \"lib2.js\" in 7"
 
 # sandboxing
 
 njs_test {
     {"var fs = require('fs')\r\n"
-     "Error: Cannot find module \"fs\"\r\n"}
+     "Error: Cannot load module \"fs\"\r\n"}
 } "-s"
 
 njs_test {