[FL-2059] Storage fixes for handling empty files (#1563)

* storage: fixed handling of zero-length files
* docs: added ReadMe.md for vscode workspace
* rpc: storage: improved empty file & error handling in write handler
* docs: markdown fix
* docs: typo fixes

Co-authored-by: SG <who.just.the.doctor@gmail.com>
Co-authored-by: あく <alleteam@gmail.com>

lib/toolbox/path.c

@@ -85,6 +85,10 @@ void path_concat(const char* path, const char* suffix, string_t out_path) {
 }
 
 bool path_contains_only_ascii(const char* path) {
+    if(!path) {
+        return false;
+    }
+
     const char* name_pos = strrchr(path, '/');
     if(name_pos == NULL) {
         name_pos = path;