Error Handling — Simple

flowchart LR
  Op[Operation]
  OK([Success])
  ERR([Failure])
  RES([Result / Either])
  Op --> OK
  Op --> ERR
  OK --> RES
  ERR --> RES
  RES --> Caller

  classDef p fill:#dbeafe,stroke:#1e40af,stroke-width:1px,color:#0f172a;
  classDef s fill:#fef3c7,stroke:#92400e,stroke-width:1px,color:#0f172a;
  classDef ok fill:#d1fae5,stroke:#065f46,stroke-width:1px,color:#0f172a;
  classDef err fill:#fee2e2,stroke:#991b1b,stroke-width:1px,color:#0f172a;
  class Op s;
  class Caller p;
  class OK,RES ok;
  class ERR err;

    classDef client fill:#dbeafe,stroke:#1e40af,stroke-width:1px,color:#0f172a;
    classDef edge fill:#cffafe,stroke:#0e7490,stroke-width:1px,color:#0f172a;
    classDef service fill:#fef3c7,stroke:#92400e,stroke-width:1px,color:#0f172a;
    classDef datastore fill:#fee2e2,stroke:#991b1b,stroke-width:1px,color:#0f172a;
    classDef cache fill:#fed7aa,stroke:#9a3412,stroke-width:1px,color:#0f172a;
    classDef queue fill:#ede9fe,stroke:#5b21b6,stroke-width:1px,color:#0f172a;
    classDef compute fill:#d1fae5,stroke:#065f46,stroke-width:1px,color:#0f172a;
    classDef storage fill:#e5e7eb,stroke:#374151,stroke-width:1px,color:#0f172a;
    classDef external fill:#fce7f3,stroke:#9d174d,stroke-width:1px,color:#0f172a;
    classDef obs fill:#f3e8ff,stroke:#6b21a8,stroke-width:1px,color:#0f172a;
    class Op,OK,ERR,RES service;

Failures are inevitable. Make them explicit in the type system (Result / Either / Option) or explicit in the API (typed exceptions). Hidden failures = production fires.