Fix LSP semantic coloration bailing out sometimes

Step to reproduce:

```
xx := Window {
   TouchArea {
      clicked => {
         if (true) {}
         // note: because there is no else, the semantic colouring is bailing out now
      }
   }
   TouchArea { clicked => {} }
}
```

This is caused by a bug in rowan::SyntaxToken::next_token that doesn't visit
the next token if it has an empty node

Unfortunately, the LSP has no tests, so I couldn't add one easily

Author: ogoffart

internal/compiler/parser.rs

@@ -693,6 +693,31 @@ impl SyntaxToken {
     pub fn parent(&self) -> SyntaxNode {
         SyntaxNode { node: self.token.parent().unwrap(), source_file: self.source_file.clone() }
     }
+    pub fn next_token(&self) -> Option<SyntaxToken> {
+        // Due to a bug (as of rowan 0.15.3), rowan::SyntaxToken::next_token doesn't work if a
+        // sibling don't have tokens.
+        // For example, if we have an expression like  `if (true) {}`  the
+        // ConditionalExpression has an empty Expression/CodeBlock  for the else part,
+        // and next_token doesn't go into that.
+        // So re-implement
+
+        let token = self
+            .token
+            .next_sibling_or_token()
+            .and_then(|e| match e {
+                rowan::NodeOrToken::Node(n) => n.first_token(),
+                rowan::NodeOrToken::Token(t) => Some(t),
+            })
+            .or_else(|| {
+                self.token.ancestors().find_map(|it| it.next_sibling_or_token()).and_then(|e| {
+                    match e {
+                        rowan::NodeOrToken::Node(n) => n.first_token(),
+                        rowan::NodeOrToken::Token(t) => Some(t),
+                    }
+                })
+            })?;
+        Some(SyntaxToken { token, source_file: self.source_file.clone() })
+    }
 }
 
 impl std::fmt::Display for SyntaxToken {
@@ -745,6 +770,11 @@ impl SyntaxNode {
     pub fn parent(&self) -> Option<SyntaxNode> {
         self.node.parent().map(|node| SyntaxNode { node, source_file: self.source_file.clone() })
     }
+    pub fn first_token(&self) -> Option<SyntaxToken> {
+        self.node
+            .first_token()
+            .map(|token| SyntaxToken { token, source_file: self.source_file.clone() })
+    }
 }
 
 #[derive(Debug, Clone, derive_more::From)]

tools/lsp/semantic_tokens.rs

@@ -44,7 +44,7 @@ pub fn get_semantic_tokens(
             SyntaxKind::StringLiteral => Some((self::STRING, 0)),
             SyntaxKind::NumberLiteral => Some((self::NUMBER, 0)),
             SyntaxKind::ColorLiteral => Some((self::NUMBER, 0)),
-            SyntaxKind::Identifier => match token.parent()?.kind() {
+            SyntaxKind::Identifier => match token.parent().kind() {
                 SyntaxKind::Component => Some((self::KEYWORD, 0)),
                 // the id of the element
                 SyntaxKind::SubElement => Some((self::VARIABLE, 1 << self::DEFINITION)),
@@ -55,7 +55,7 @@ pub fn get_semantic_tokens(
                 SyntaxKind::CallbackConnection => Some((self::FUNCTION, 0)),
                 SyntaxKind::PropertyDeclaration => Some((self::KEYWORD, 0)),
                 SyntaxKind::PropertyAnimation => Some((self::KEYWORD, 0)),
-                SyntaxKind::QualifiedName => match token.parent()?.parent()?.kind() {
+                SyntaxKind::QualifiedName => match token.parent().parent()?.kind() {
                     SyntaxKind::Type => Some((self::TYPE, 0)),
                     // the base type
                     SyntaxKind::Element => Some((self::TYPE, 0)),
@@ -66,7 +66,7 @@ pub fn get_semantic_tokens(
                     _ => None,
                 },
                 SyntaxKind::DeclaredIdentifier => {
-                    match token.parent()?.parent()?.kind() {
+                    match token.parent().parent()?.kind() {
                         SyntaxKind::Component => Some((self::TYPE, 1 << self::DEFINITION)),
                         SyntaxKind::RepeatedElement => {
                             Some((self::PROPERTY, 1 << self::DEFINITION))
@@ -104,7 +104,7 @@ pub fn get_semantic_tokens(
                 SyntaxKind::ExportIdentifier => {
                     Some((
                         self::TYPE,
-                        if token.parent()?.parent().map_or(false, |p| {
+                        if token.parent().parent().map_or(false, |p| {
                             p.children().any(|n| n.kind() == SyntaxKind::ExportName)
                         }) {
                             0
@@ -118,7 +118,7 @@ pub fn get_semantic_tokens(
                 SyntaxKind::ImportIdentifier => Some((self::KEYWORD, 0)),
                 SyntaxKind::ExternalName => Some((
                     self::TYPE,
-                    if token.parent()?.parent().map_or(false, |p| {
+                    if token.parent().parent().map_or(false, |p| {
                         p.children().any(|n| n.kind() == SyntaxKind::InternalName)
                     }) {
                         0
@@ -141,7 +141,7 @@ pub fn get_semantic_tokens(
             | SyntaxKind::NotEqual
             | SyntaxKind::OrOr
             | SyntaxKind::AndAnd => Some((self::OPERATOR, 0)),
-            SyntaxKind::LAngle | SyntaxKind::RAngle => (token.parent()?.kind()
+            SyntaxKind::LAngle | SyntaxKind::RAngle => (token.parent().kind()
                 == SyntaxKind::PropertyDeclaration)
                 .then(|| (self::OPERATOR, 0)),
             SyntaxKind::Plus