Support parsing empty metadata

Author: carson-katri

Sources/LiveViewNativeStylesheet/Parsing/External/Metadata.swift

@@ -7,48 +7,53 @@ public struct Metadata {
     public let source: String
 
     public static func parser() -> some Parser<Substring.UTF8View, Self> {
-        Parse { (file, line, module, source) in
-            Self(file: file, line: line, module: module, source: source)
-        } with: {
-            "[".utf8
-            
-            Whitespace()
-            "file:".utf8
-            Whitespace()
-            StringLiteral()
-            Whitespace()
-            ",".utf8
-            
-            Whitespace()
-            
-            "line:".utf8
-            Whitespace()
-            Parsers.IntParser<Substring.UTF8View, Int>()
-            Whitespace()
-            ",".utf8
-            
-            Whitespace()
-            
-            "module:".utf8
-            Whitespace()
-            Many {
-                Identifier()
-            } separator: {
-                ".".utf8
+        OneOf {
+            Parse { (file, line, module, source) in
+                Self(file: file, line: line, module: module, source: source)
+            } with: {
+                "[".utf8
+                
+                Whitespace()
+                "file:".utf8
+                Whitespace()
+                StringLiteral()
+                Whitespace()
+                ",".utf8
+                
+                Whitespace()
+                
+                "line:".utf8
+                Whitespace()
+                Parsers.IntParser<Substring.UTF8View, Int>()
+                Whitespace()
+                ",".utf8
+                
+                Whitespace()
+                
+                "module:".utf8
+                Whitespace()
+                Many {
+                    Identifier()
+                } separator: {
+                    ".".utf8
+                }
+                .map({ $0.joined(separator: ".") })
+                Whitespace()
+                ",".utf8
+                
+                Whitespace()
+                
+                "source:".utf8
+                Whitespace()
+                StringLiteral()
+                
+                Whitespace()
+                
+                "]".utf8
+            }
+            "[]".utf8.map {
+                Self.init(file: "", line: 0, module: "", source: "")
             }
-            .map({ $0.joined(separator: ".") })
-            Whitespace()
-            ",".utf8
-            
-            Whitespace()
-            
-            "source:".utf8
-            Whitespace()
-            StringLiteral()
-            
-            Whitespace()
-            
-            "]".utf8
         }
     }
 }