add tests for fuzzed results, clean up unimplemented osc warning

src/Command.zig

@@ -255,6 +255,9 @@ pub fn expandPath(alloc: Allocator, cmd: []const u8) !?[]u8 {
         path_buf[path_len] = 0;
         const full_path = path_buf[0..path_len :0];
 
+        // Skip if this isn't an absolute path
+        if (!std.fs.path.isAbsolute(full_path)) continue;
+
         // Stat it
         const f = std.fs.openFileAbsolute(full_path, .{}) catch |err| switch (err) {
             error.FileNotFound => continue,