[VarDumper] Fix indentation trimming in ExceptionCaster

src/Symfony/Component/VarDumper/Caster/ExceptionCaster.php

@@ -253,19 +253,24 @@ class ExceptionCaster
         }
 
         $ltrim = 0;
-        while (' ' === $src[0][$ltrim] || "\t" === $src[0][$ltrim]) {
-            $i = $srcContext << 1;
-            while ($i > 0 && $src[0][$ltrim] === $src[$i][$ltrim]) {
-                --$i;
+        do {
+            $pad = null;
+            for ($i = $srcContext << 1; $i >= 0; --$i) {
+                if (isset($src[$i][$ltrim]) && "\r" !== ($c = $src[$i][$ltrim]) && "\n" !== $c) {
+                    if (null === $pad) {
+                        $pad = $c;
                     }
-            if ($i) {
+                    if ((' ' !== $c && "\t" !== $c) || $pad !== $c) {
                         break;
                     }
-            ++$ltrim;
                 }
-        if ($ltrim) {
+            }
+            ++$ltrim;
+        } while (0 > $i && null !== $pad);
+
+        if (--$ltrim) {
             foreach ($src as $i => $line) {
-                $src[$i] = substr($line, $ltrim);
+                $src[$i] = isset($line[$ltrim]) && "\r" !== $line[$ltrim] ? substr($line, $ltrim) : ltrim($line, " \t");
             }
         }