diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1fef0a71..5e0b9937 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -90,8 +90,8 @@ jobs:
         #   https://github.com/rust-lang/rustup/issues/2441
         #
         # for more information.
-        rustup toolchain install 1.88.0 --no-self-update # [ref:rust_1.88.0]
-        rustup default 1.88.0 # [ref:rust_1.88.0]
+        rustup toolchain install 1.91.0 --no-self-update # [ref:rust_1.91.0]
+        rustup default 1.91.0 # [ref:rust_1.91.0]
 
         # Add the targets.
         rustup target add x86_64-pc-windows-msvc
@@ -131,8 +131,8 @@ jobs:
         set -euxo pipefail
 
         # Install the appropriate version of Rust.
-        rustup toolchain install 1.88.0 # [ref:rust_1.88.0]
-        rustup default 1.88.0 # [ref:rust_1.88.0]
+        rustup toolchain install 1.91.0 # [ref:rust_1.91.0]
+        rustup default 1.91.0 # [ref:rust_1.91.0]
 
         # Add the targets.
         rustup target add x86_64-apple-darwin
@@ -207,8 +207,8 @@ jobs:
         set -euxo pipefail
 
         # Install the appropriate version of Rust.
-        rustup toolchain install 1.88.0 # [ref:rust_1.88.0]
-        rustup default 1.88.0 # [ref:rust_1.88.0]
+        rustup toolchain install 1.91.0 # [ref:rust_1.91.0]
+        rustup default 1.91.0 # [ref:rust_1.91.0]
 
         # Fetch the program version.
         VERSION="$(cargo pkgid | cut -d# -f2 | cut -d: -f2)"
diff --git a/src/parser.rs b/src/parser.rs
index 7a94a513..29a83968 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -244,27 +244,27 @@ fn parse_schema(
     let mut declarations = vec![];
 
     // Parse the comment, if it exists.
-    if *position < tokens.len() {
-        if let token::Variant::Comment(paragraphs) = &tokens[*position].variant {
-            if *position + 1 < tokens.len() {
-                match tokens[*position + 1].variant {
-                    token::Variant::Struct | token::Variant::Choice => {
-                        if tokens[*position].source_range.end + 1
-                            < tokens[*position + 1].source_range.start
-                        {
-                            comment.clone_from(paragraphs);
-                            *position += 1;
-                        }
-                    }
-                    _ => {
+    if *position < tokens.len()
+        && let token::Variant::Comment(paragraphs) = &tokens[*position].variant
+    {
+        if *position + 1 < tokens.len() {
+            match tokens[*position + 1].variant {
+                token::Variant::Struct | token::Variant::Choice => {
+                    if tokens[*position].source_range.end + 1
+                        < tokens[*position + 1].source_range.start
+                    {
                         comment.clone_from(paragraphs);
                         *position += 1;
                     }
                 }
-            } else {
-                comment.clone_from(paragraphs);
-                *position += 1;
+                _ => {
+                    comment.clone_from(paragraphs);
+                    *position += 1;
+                }
             }
+        } else {
+            comment.clone_from(paragraphs);
+            *position += 1;
         }
     }
 
@@ -276,18 +276,17 @@ fn parse_schema(
                 // [ref:parse_import_keyword_chomp].
                 if let Some((name, import)) =
                     parse_import(source_path, source_contents, tokens, position, errors)
+                    && imports.insert(name.clone(), import.clone()).is_some()
                 {
-                    if imports.insert(name.clone(), import.clone()).is_some() {
-                        errors.push(throw::<Error>(
-                            &format!(
-                                "An import named {} already exists in this file.",
-                                name.code_str(),
-                            ),
-                            Some(source_path),
-                            Some(&listing(source_contents, import.source_range)),
-                            None,
-                        ));
-                    }
+                    errors.push(throw::<Error>(
+                        &format!(
+                            "An import named {} already exists in this file.",
+                            name.code_str(),
+                        ),
+                        Some(source_path),
+                        Some(&listing(source_contents, import.source_range)),
+                        None,
+                    ));
                 }
             }
             _ => {
diff --git a/toast.yml b/toast.yml
index 75c9e0ec..de606e4a 100644
--- a/toast.yml
+++ b/toast.yml
@@ -17,11 +17,11 @@ command_prefix: |
   cargo-offline () { cargo --frozen --offline "$@"; }
 
   # Use this wrapper for formatting code or checking that code is formatted. We use a nightly Rust
-  # version for the `trailing_comma` formatting option [tag:rust_fmt_nightly_2025-07-06]. The
+  # version for the `trailing_comma` formatting option [tag:rust_fmt_nightly_2025-11-02]. The
   # nightly version was chosen as the latest available release with all components present
   # according to this page:
   #   https://rust-lang.github.io/rustup-components-history/x86_64-unknown-linux-gnu.html
-  cargo-fmt () { cargo +nightly-2025-07-06 --frozen --offline fmt --all -- "$@"; }
+  cargo-fmt () { cargo +nightly-2025-11-02 --frozen --offline fmt --all -- "$@"; }
 
   # Load the NVM startup file, if it exists.
   if [ -f "$HOME/.nvm/nvm.sh" ]; then
@@ -75,18 +75,18 @@ tasks:
       - install_packages
       - create_user
     command: |
-      # Install stable Rust [tag:rust_1.88.0].
+      # Install stable Rust [tag:rust_1.91.0].
       curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- \
         -y \
-        --default-toolchain 1.88.0 \
+        --default-toolchain 1.91.0 \
         --profile minimal \
         --component clippy
 
       # Add Rust tools to `$PATH`.
       . "$HOME/.cargo/env"
 
-      # Install nightly Rust [ref:rust_fmt_nightly_2025-07-06].
-      rustup toolchain install nightly-2025-07-06 --profile minimal --component rustfmt
+      # Install nightly Rust [ref:rust_fmt_nightly_2025-11-02].
+      rustup toolchain install nightly-2025-11-02 --profile minimal --component rustfmt
 
   install_node:
     description: Install Node.js, a JavaScript runtime environment.