fix: normalize non-numeric body dimension values of existing drafts

src/Form/Model/ParticipantDto.php

@@ -360,6 +360,61 @@ class ParticipantDto
         return $ageThreshold > $age;
     }
 
+    /**
+     * Normalizes body-dimension fields to canonical string values.
+     *
+     * Keeps plain integers and digit-only strings, converting them to a
+     * normalized string representation. Anything else is treated as legacy
+     * garbage and reset to null so form hydration can continue safely.
+     */
+    public function normalizeBodyDimensions(): void
+    {
+        $this->height = $this->normalizeBodyDimensionValue($this->height);
+        $this->weight = $this->normalizeBodyDimensionValue($this->weight);
+        $this->shoeSize = $this->normalizeBodyDimensionValue($this->shoeSize);
+    }
+
+    /**
+     * Restores the DTO from session/serialization data.
+     *
+     * @param array<string, mixed> $data
+     */
+    public function __unserialize(array $data): void
+    {
+        foreach ($data as $key => $value) {
+            if (false === property_exists($this, $key)) {
+                continue;
+            }
+
+            $this->$key = $value;
+        }
+
+        if (false === isset($this->address)) {
+            $this->address = new Address();
+        }
+
+        // TODO: Remove after all legacy drafts/session snapshots with body-dimension strings have expired.
+        $this->normalizeBodyDimensions();
+    }
+
+    private function normalizeBodyDimensionValue(mixed $value): ?string
+    {
+        if (true === is_int($value)) {
+            return (string) $value;
+        }
+
+        if (false === is_string($value)) {
+            return null;
+        }
+
+        $value = trim($value);
+        if ('' === $value || false === ctype_digit($value)) {
+            return null;
+        }
+
+        return (string) (int) $value;
+    }
+
     /**
      * Validates that the applicant (index 0) has a complete address.
      *