fix(api): return 200 with embedded log on SAS session failure instead of 400

A failed session (e.g. SAS %abort;, or a non-zero JS/PY/R exit) is a
normal outcome of running arbitrary user code, not a request-shape or
server problem. The #388 fix stopped processProgram() from hanging
forever on a failed SAS session, but did so by throwing a
SessionExecutionError, which surfaced as an HTTP 400 with a bespoke
JSON shape - breaking Studio's log tab, which only renders on 2xx.

Align the SAS branch with the pre-existing JS/PY/R behaviour: resolve
instead of throwing, and let Execution.ts fold session.failureReason
into the log the same way it already does for a debug-mode run. This
removes the now-dead SessionExecutionError class and its try/catch
wrapper entirely.

Update the diagrams in api/docs/diagrams/ to match.

api/src/controllers/internal/spec/Execution.spec.ts

@@ -2,7 +2,7 @@ import path from 'path'
 import os from 'os'
 import { createFile, deleteFolder, generateTimestamp } from '@sasjs/utils'
 import * as ProcessProgramModule from '../processProgram'
-import { ExecutionController, SessionExecutionError } from '../Execution'
+import { ExecutionController } from '../Execution'
 import { Session, SessionState, PreProgramVars } from '../../../types'
 import { RunTimeType } from '../../../utils'
 
@@ -83,8 +83,15 @@ describe('ExecutionController.executeProgram', () => {
     })
   })
 
+  // A failed SAS session (e.g. from %abort;) is a normal outcome of
+  // running arbitrary user code, not a request-shape/server problem - the
+  // same way a plain SAS ERROR: in the log (without %abort;) already
+  // returns 200 with the log embedded. This mirrors the JS/PY/R failure
+  // path above: resolve normally, don't throw, and let the existing
+  // session.failureReason check below produce the same result shape as a
+  // successful run.
   describe('SAS failure path', () => {
-    it('throws a SessionExecutionError carrying the complete log when the session fails', async () => {
+    it('returns the complete log embedded in a normal result instead of throwing, when the session fails', async () => {
       const logPath = path.join(session.path, 'log.log')
       const logContent =
         'NOTE: SAS session\nERROR: SAS session terminated. See log for details.\n'
@@ -94,12 +101,17 @@ describe('ExecutionController.executeProgram', () => {
       jest
         .spyOn(ProcessProgramModule, 'processProgram')
         .mockImplementation(async () => {
-          throw new Error('ERROR: SAS session terminated. See log for details.')
+          // mirrors the real SAS branch after the fix: sets
+          // state/failureReason and resolves, exactly like the JS/PY/R
+          // branch already does - it does not throw
+          session.state = SessionState.failed
+          session.failureReason =
+            'ERROR: SAS session terminated. See log for details.'
         })
 
       const controller = new ExecutionController()
 
-      const resultPromise = controller.executeProgram({
+      const { result } = await controller.executeProgram({
         program: '%abort;',
         preProgramVariables,
         vars: {},
@@ -107,11 +119,8 @@ describe('ExecutionController.executeProgram', () => {
         runTime: RunTimeType.SAS
       })
 
-      await expect(resultPromise).rejects.toBeInstanceOf(SessionExecutionError)
-      await expect(resultPromise).rejects.toMatchObject({
-        log: logContent,
-        message: expect.stringContaining('SAS session terminated')
-      })
+      expect(session.state).toBe(SessionState.failed)
+      expect(result).toEqual(expect.stringContaining(logContent))
     })
   })
 })