Add proper error for unsupported targets

2 files changed, 12 insertions, 2 deletions

diff --git a/src/main/java/org/shedlang/compiler/cli/ShedCli.java b/src/main/java/org/shedlang/compiler/cli/ShedCli.java
index 7f6d88ad..9ae3fb75 100644
--- a/src/main/java/org/shedlang/compiler/cli/ShedCli.java
+++ b/src/main/java/org/shedlang/compiler/cli/ShedCli.java
@@ -44,8 +44,7 @@ public class ShedCli {
                                 // In principle, this should be prevented by the arg parsing.
                                 .orElseThrow(() -> new UnsupportedOperationException("Unrecognised backend: " + backendName))
                                 .backendForTarget(target)
-                                // TODO: better error
-                                .orElseThrow(() -> new UnsupportedOperationException("Backend " + backendName + " does not support target " + target.targetName()))
+                                .orElseThrow(() -> new UnsupportedTargetError(backendName, target))
                     )
                     .orElseGet(() -> Backends.backendForTarget(target));
                 var profile = Optional.ofNullable(args.getString("profile"));
diff --git a/src/main/java/org/shedlang/compiler/cli/UnsupportedTargetError.java b/src/main/java/org/shedlang/compiler/cli/UnsupportedTargetError.java
new file mode 100644
index 00000000..265c2cdc
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/cli/UnsupportedTargetError.java
@@ -0,0 +1,11 @@
+package org.shedlang.compiler.cli;
+
+import org.shedlang.compiler.backends.ShedTarget;
+import org.shedlang.compiler.errors.CompilerError;
+import org.shedlang.compiler.sources.Sources;
+
+public class UnsupportedTargetError extends CompilerError {
+    public UnsupportedTargetError(String backendName, ShedTarget target) {
+        super("Backend " + backendName + " does not support target " + target.targetName(), Sources.NULL);
+    }
+}