Remove temp buffer in WiFiClientSecure::lastError (#4822)

The temp buffer serves no purpose here. Also mbedtls_strerror can be called with size == 0 safely.

Author: everslick

Diff for: libraries/WiFiClientSecure/src/WiFiClientSecure.cpp

@@ -333,9 +333,7 @@ int WiFiClientSecure::lastError(char *buf, const size_t size)
     if (!_lastError) {
         return 0;
     }
-    char error_buf[100];
-    mbedtls_strerror(_lastError, error_buf, 100);
-    snprintf(buf, size, "%s", error_buf);
+    mbedtls_strerror(_lastError, buf, size);
     return _lastError;
 }