Impl: Check for wrong input characters

src/main.rs

@@ -1,7 +1,5 @@
 use clap::Parser;
 
-use regex::Regex;
-
 #[derive(Parser)]
 #[command(version, about, long_about = None)]
 struct Cli {
@@ -87,7 +85,12 @@ fn parse_playfield(field: &String, field_size: usize) -> Playfield {
                 continue;
             }
 
-            field.value = Some(char_field.parse().unwrap());
+            field.value = Some(char_field.parse().unwrap_or_else(|char_field| {
+                panic!(
+                    "Input must contain only digits followed by space. Disallowed character: {}",
+                    char_field
+                )
+            }));
         }
     }
 
@@ -132,7 +135,7 @@ mod tests {
     }
 
     #[test]
-    #[should_panic(expected = "Input must have dimension of size 2x2")]
+    #[should_panic(expected = "Input must have dimension of size 3x3")]
     fn test_parse_field_too_short_input() {
         let input = "1 2 3";
         let field_size = 3;