Handle failure to find procedure. Fixes #282

If no parameters are found, assume the schema name is incorrect and don't populate the cache. This will require the user to supply the stored procedure's parameters in the correct order (but that will be successful).

Additionally, skip parameter lookup if the schema name is unknown (since that will always fail).

Author: bgrainger

src/MySqlConnector/Core/CachedProcedure.cs

@@ -48,7 +48,7 @@ FROM information_schema.parameters
 				}
 			}
 
-			return new CachedProcedure(schema, component, parameters.AsReadOnly());
+			return parameters.Count == 0 ? null : new CachedProcedure(schema, component, parameters.AsReadOnly());
 		}
 
 		private CachedProcedure(string schema, string component, ReadOnlyCollection<CachedParameter> parameters)

src/MySqlConnector/MySql.Data.MySqlClient/MySqlConnection.cs

@@ -307,6 +307,9 @@ internal async Task<CachedProcedure> GetCachedProcedure(IOBehavior ioBehavior, s
 				cachedProcedures = m_cachedProcedures = new Dictionary<string, CachedProcedure>();
 
 			var normalized = NormalizedSchema.MustNormalize(name, Database);
+			if (string.IsNullOrEmpty(normalized.Schema))
+				return null;
+
 			CachedProcedure cachedProcedure;
 			lock (cachedProcedures)
 				cachedProcedures.TryGetValue(normalized.FullyQualified, out cachedProcedure);