Fix OOB error

This was introduced by the removal of `get_loc_by_language`, which had
a check to return `None` if the total LoC was `0`. This will now check
if the list of languages is empty.

src/info/langs/mod.rs

@@ -1,4 +1,4 @@
-use anyhow::{anyhow, Result};
+use anyhow::{anyhow, Context, Result};
 use gengo::{Builder, Git};
 
 use globset::{Glob, GlobSetBuilder};
@@ -9,8 +9,12 @@ use std::path::Path;
 
 pub mod language;
 
-pub fn get_main_language(size_by_language: &[(Language, usize)]) -> Language {
-    size_by_language[0].0
+pub fn get_main_language(size_by_language: &[(Language, usize)]) -> Result<Language> {
+    // TODO This function only works with an already-sorted slice, so it doesn't have much utility
+    let (language, _) = size_by_language
+        .get(0)
+        .context("Could not find any source code in this repository")?;
+    Ok(*language)
 }
 
 /// Returns a vector of tuples containing all the languages detected inside the repository.

src/info/mod.rs

@@ -158,7 +158,7 @@ pub fn build_info(cli_options: &CliOptions) -> Result<Info> {
         When::Never => false,
         When::Auto => is_truecolor_terminal(),
     };
-    let dominant_language = langs::get_main_language(&size_by_language);
+    let dominant_language = langs::get_main_language(&size_by_language)?;
     let ascii_colors = get_ascii_colors(
         &cli_options.ascii.ascii_language,
         &dominant_language,