fix: always early exit if no sources to lint

Author: 0xrusowsky

crates/forge/src/cmd/build.rs

@@ -176,8 +176,12 @@ impl BuildArgs {
 
             let solar_sources =
                 get_solar_sources_from_compile_output(config, output, Some(&input_files))?;
-            if solar_sources.input.sources.is_empty() && !input_files.is_empty() {
-                sh_warn!("unable to lint. Solar only supports Solidity versions prior to 0.8.0")?;
+            if solar_sources.input.sources.is_empty() {
+                if !input_files.is_empty() {
+                    sh_warn!(
+                        "unable to lint. Solar only supports Solidity versions prior to 0.8.0"
+                    )?;
+                }
                 return Ok(());
             }