* Return a human-readable error string for the given libsigrok error code.
*
* @param error_code A libsigrok error code number, such as SR_ERR_MALLOC.
* Return a human-readable error string for the given libsigrok error code.
*
* @param error_code A libsigrok error code number, such as SR_ERR_MALLOC.
* @return A const string containing a short, human-readable (English)
* description of the error, such as "memory allocation error".
* The string must NOT be free'd by the caller!
* @return A const string containing a short, human-readable (English)
* description of the error, such as "memory allocation error".
* The string must NOT be free'd by the caller!
* a libsigrok error code is useful.
*
* @param error_code A libsigrok error code number, such as SR_ERR_MALLOC.
* a libsigrok error code is useful.
*
* @param error_code A libsigrok error code number, such as SR_ERR_MALLOC.
* @return A const string containing the "name" of the error code as string.
* The string must NOT be free'd by the caller!
* @return A const string containing the "name" of the error code as string.
* The string must NOT be free'd by the caller!