Errors

Arc error code reference for compile-time and runtime errors

Arc errors fall into two categories: compile-time errors (caught before deployment) and runtime errors (occur during execution).

Error code format

Arc error codes follow the pattern:

ARC<category><number>

Compile-time errors

The compiler catches these before deployment.

Type system errors (ARC2xxx)

Example: TypeMismatch

// Error: cannot add i32 and f64
x i32 := 42
y f64 := x + 1.0

Fix: Use explicit type casting:

x i32 := 42
y f64 := f64(x) + 1.0

Function errors (ARC3xxx)

Example: FuncArgCount

func add(x f64, y f64) f64 {
    return x + y
}
// Error: expected 2 arguments, got 1
result := add(5.0)

Symbol errors (ARC4xxx)

Example: SymbolUndefined

// Error: undefined symbol 'ox_pt_1'
value := ox_pt_1 // channel doesn't exist in cluster

Example: SymbolRedefined

x := 42
x := 100 // Error: x already declared

func example() {
    x := 10
    if x > 0 {
        x := 20 // Error: conflicts with outer x
    }
}

Common error messages

Runtime errors

These errors occur during execution and stop the Arc task (but not the Driver).

Arithmetic errors

// Runtime error if b is 0
result := a / b

Prevention:

if b != 0 {
    result := a / b
}

Array/string errors

data := [1.0, 2.0, 3.0]
value := data[5] // Runtime error: index 5 out of bounds

Prevention:

if index < len(data) {
    value := data[index]
}

Error isolation

A runtime error in one Arc task only stops that task. Other tasks and the hardware driver continue running normally. The error status is reported to Console where you can see what went wrong.

Debugging

Check task status

When an Arc automation doesn’t behave as expected:

1. Check the task status in Console
2. Runtime errors (division by zero, out-of-bounds) stop the task and report the error
3. The error message indicates what went wrong

Use LSP diagnostics

The text editor shows compile-time errors inline:

• Red underline: Error (won’t compile)
• Yellow underline: Warning (compiles but suspicious)
• Hover for error message and suggested fix

Write intermediate values

Write intermediate values to channels for debugging:

func debug_controller(value f64) f64 {
    error := value - setpoint

    // Write to channel for visibility
    debug_error = f"Error is: {error}"
    return error * gain
}

Monitor these channels in Console to trace data flow.

Common fixes