fix: correct off-by-one error in findErrorBlockEnd defer insertion

The defer sess.Release() statements were being inserted inside error blocks
instead of after them, making the defer unreachable. This fixes the line
number mapping from AST positions back to the original lines array by
removing the unnecessary -1 offset.

Author: sixcolors

cmd/internal/migrations/v3/session_release.go

@@ -349,7 +349,7 @@ func findErrorBlockEnd(lines []string, startIdx int) int {
 			pos := fset.Position(ifStmt.Body.End())
 			lineNum := pos.Line - 3
 			if lineNum >= 0 {
-				ifStmtEnd = snippetStartLine + lineNum - 1
+				ifStmtEnd = snippetStartLine + lineNum
 				return false
 			}
 		}