core, plugins: check that string parameters are not NULL in search functions (issue #1872)

src/plugins/script/script.c

@@ -67,6 +67,9 @@ script_language_search (const char *language)
 {
     int i;
 
+    if (!language)
+        return -1;
+
     for (i = 0; i < SCRIPT_NUM_LANGUAGES; i++)
     {
         if (strcmp (script_language[i], language) == 0)
@@ -88,6 +91,9 @@ script_language_search_by_extension (const char *extension)
 {
     int i;
 
+    if (!extension)
+        return -1;
+
     for (i = 0; i < SCRIPT_NUM_LANGUAGES; i++)
     {
         if (strcmp (script_extension[i], extension) == 0)