Add specific error handling and message for MDBX_MAP_FULL scenario. (#160)

* Add specific error handling and message for MDBX_MAP_FULL scenario.

* Clarify and expand the MapFullErrorRecommendation message for better guidance.

* Simplify MapFull error message and update variable name accordingly.

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Co-authored-by: JkLondon <ilya@mikheev.fun>

Author: JkLondon

mdbx/error.go

@@ -84,15 +84,19 @@ var CorruptErrorHardwareRecommendations = "Maybe free space is over on disk. Oth
 var CorruptErrorBacktraceRecommendations = "Otherwise - please create issue in Application repo." // with backtrace or coredump. To create coredump set compile option 'MDBX_FORCE_ASSERTIONS=1' and env variable 'GOTRACEBACK=crash'."
 var CorruptErrorRecoveryRecommendations = "On default DURABLE mode, power outage can't cause this error. On other modes - power outage may break last transaction and mdbx_chk can recover db in this case, see '-t' and '-0|1|2' options."
 var CorruptErrorMessage = CorruptErrorHardwareRecommendations + " " + CorruptErrorBacktraceRecommendations + " " + CorruptErrorRecoveryRecommendations
+var MapFullErrorMessage = "The allocated database storage size limit has been reached."
 
 func (e Errno) Error() string {
-	if e == Corrupted {
+	switch e {
+	case Corrupted:
 		return fmt.Sprintf("MDBX_FATAL(%d): ", int(e)) + CorruptErrorMessage
-	}
-	if e == Panic {
+	case Panic:
 		return fmt.Sprintf("MDBX_PANIC(%d): ", int(e)) + CorruptErrorMessage
+	case MapFull:
+		return fmt.Sprintf("MDBX_MAP_FULL(%d)", int(e)) + MapFullErrorMessage
+	default:
+		return C.GoString(C.mdbx_strerror(C.int(e)))
 	}
-	return C.GoString(C.mdbx_strerror(C.int(e)))
 }
 
 // _operrno is for use by tests that can't import C