Learn a bit from clippy.

src/bin/accounting.rs

@@ -121,8 +121,7 @@ fn next_target(low_index: usize, high_index: usize, avoid: &[usize]) -> Option<u
 }
 
 fn main() {
-    match real_main() {
-        Err(e) => eprintln!("ERROR: {}", e),
-        Ok(_) => {}
+    if let Err(e) = real_main() {
+        eprintln!("ERROR: {}", e);
     }
 }

src/bin/boarding_pass.rs

@@ -150,8 +150,7 @@ fn real_main() -> Result<(), TopLevelError> {
 }
 
 fn main() {
-    match real_main() {
-        Err(e) => eprintln!("ERROR: {}", e),
-        Ok(_) => {}
+    if let Err(e) = real_main() {
+        eprintln!("ERROR: {}", e);
     }
 }

src/bin/passport.rs

@@ -172,8 +172,7 @@ fn real_main() -> Result<(), TopLevelError> {
 }
 
 fn main() {
-    match real_main() {
-        Err(e) => eprintln!("ERROR: {}", e),
-        Ok(_) => {}
+    if let Err(e) = real_main() {
+        eprintln!("ERROR: {}", e);
     }
 }

src/bin/password_check.rs

@@ -99,8 +99,7 @@ fn real_main() -> Result<(), TopLevelError> {
 }
 
 fn main() {
-    match real_main() {
-        Err(e) => eprintln!("ERROR: {}", e),
-        Ok(_) => {}
+    if let Err(e) = real_main() {
+        eprintln!("ERROR: {}", e);
     }
 }

src/bin/tobaggan.rs

@@ -93,8 +93,7 @@ fn real_main() -> Result<(), TopLevelError> {
 }
 
 fn main() {
-    match real_main() {
-        Err(e) => eprintln!("ERROR: {}", e),
-        Ok(_) => {}
+    if let Err(e) = real_main() {
+        eprintln!("ERROR: {}", e);
     }
 }