Added float comparison null checks (#33421)

Author: GrahamCampbell

src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php

@@ -1179,6 +1179,10 @@ public function originalIsEquivalent($key, $current)
             return $this->castAttribute($key, $current) ==
                 $this->castAttribute($key, $original);
         } elseif ($this->hasCast($key, ['real', 'float', 'double'])) {
+            if (($current === null && $original !== null) || ($current !== null && $original === null)) {
+                return false;
+            }
+
             return abs($this->castAttribute($key, $current) - $this->castAttribute($key, $original)) < PHP_FLOAT_EPSILON * 4;
         } elseif ($this->hasCast($key)) {
             return $this->castAttribute($key, $current) ===