JavaScript: don't make null tags

[masatake]

With ctags built with --enable-debugging, the following input hits an Assert:

const { extendDefaultPlugins } = require( 'svgo' );

ctags: Warning: ignoring null tag in /tmp/foo.js(line: 1)
ctags: main/entry.c:1454: registerEntry: Assertion `corkIndex != CORK_NIL' failed.
ctags: main/entry.c:1454: parsing /tmp/foo.js:1 as JavaScript
zsh: IOT instruction (core dumped)  ./ctags /tmp/foo.js

With the following change, we can avoid the crash:

diff --git a/parsers/jscript.c b/parsers/jscript.c
index c226d651b..06a2204b4 100644
--- a/parsers/jscript.c
+++ b/parsers/jscript.c
@@ -451,6 +451,8 @@ static int makeJsRefTagsForNameChain (char *name_chain, const tokenInfo *token,
        char *next = strchr(name_chain, '.');
        if (next)
                *next = '\0';
+       if (!*name)
+               return CORK_NIL;
        int index = bestJSEntryInScope (scope, name);
 
        if (index == CORK_NIL)
@@ -488,6 +490,8 @@ static int makeJsTagCommon (const tokenInfo *const token, const jsKind kind,
 {
        int index = CORK_NIL;
        const char *name = vStringValue (token->string);
+       if (!*name)
+               return CORK_NIL;
 
        const char *p;
        char *name_chain = NULL;

However, I wonder whether we should fix these callees receiving empty names or callers passing empty names. See is strongly related to #900

Of course, ctags should be able to extract extendDefaultPlugins. However, it is not the point of this issue. See #1112.

[masatake]

I would like to withdraw this because fixing callers is better.