Improve test coverage

src/MD_STD_IN.php

@@ -351,7 +351,7 @@ public static function sanitize_float(string $input):float {
 
         $output = \str_replace(",", ".", $input);
         if (($output = \filter_var($output, FILTER_VALIDATE_FLOAT)) === false) {
-            throw new MDgenericInvalidInputsException("Input is readable as a floating point value");
+            throw new MDgenericInvalidInputsException("Input is not readable as a floating point value");
         }
         return $output;