add some validation to row edit, better handle setting null cols with empty

app/Tables/Changeset.php

@@ -325,8 +325,12 @@ class Changeset
         foreach ($newVals as $colId => $value) {
             if (starts_with($colId, '_')) continue; // internals
 
-            if (!isset($origRow->$colId) || $value != $origRow->$colId) {
-                $updateObj[$colId] = $cols[$colId]->cast($value);
+            $col = $cols[$colId];
+            $value = $col->cast($value);
+            $origValue = $col->cast(isset($origRow->$colId) ? $origRow->$colId : null);
+
+            if ($value !== $origValue) {
+                $updateObj[$colId] = $value;
             }
         }
 

app/Tables/Column.php

@@ -4,6 +4,7 @@ namespace App\Tables;
 
 use Illuminate\Contracts\Support\Arrayable;
 use JsonSerializable;
+use MightyPork\Exceptions\SimpleValidationException;
 use MightyPork\Exceptions\NotApplicableException;
 use MightyPork\Utils\Utils;
 
@@ -172,13 +173,13 @@ class Column implements JsonSerializable, Arrayable
                 if (is_int($value)) return $value;
                 if (is_float($value)) return round($value);
                 if (is_numeric($value)) return intval($value);
-                throw new NotApplicableException("Could not convert value \"$value\" to int!");
+                throw new SimpleValidationException($this->id, "Could not convert value \"$value\" to int!");
 
             case 'float':
                 if (is_null($value)) return 0;
                 if (is_int($value) || is_float($value)) return (float)$value;
                 if (is_numeric($value)) return floatval($value);
-                throw new NotApplicableException("Could not convert value \"$value\" to float!");
+                throw new SimpleValidationException($this->id, "Could not convert value \"$value\" to float!");
 
             case 'bool':
                 if (is_null($value)) return false;