Q:

"npm install bcrypt" failing with "Error: Cannot find module 'nan'"

I'm trying to get my existing Angular project working on a new laptop and getting it up and running is driving me crazy.  Here is what I have done:
git init 
git clone <project>
cd <project directory>
delete package-lock.json
npm install
npm install --global --production windows-build-tools
npm install bcrypt

The penultimate step is to ensure bcrypt dependencies are installed per https://github.com/kelektiv/node.bcrypt.js/wiki/Installation-Instructions (caught me out previously).  But no matter what I try, I get the error listed at the end of this post. 
I have checked node_modules folder, and the 'nan' dependency does exist. even so, I tried installing it again (both locally and globally per node error cannot find module already installed) and it installs fine.  'nan' is also listed in the package.json file.
I have tried:
* This: Error: Cannot find module 'nan' 
* Uninstalling node like this: How to completely remove node.js from Windows
and also uninstalling all python installations I can find on the computer (including a v3 installation I thought might have been conflicting, but that doesn't seem to have been the problem).
* Other than that google is coming up blank.
* Taking a break and waiting for divine inspiration didn't work either.
Here is the error:
node-pre-gyp WARN Using request for node-pre-gyp https download
node-pre-gyp WARN Tried to download(404): https://github.com/kelektiv/node.bcrypt.js/releases/download/v3.0.3/bcrypt_lib-v3.0.3-node-v64-win32-x64-unknown.tar.gz
node-pre-gyp WARN Pre-built binaries not found for bcrypt@3.0.3 and node@10.15.0 (node-v64 ABI, unknown) (falling back to source compile with node-gyp)
internal/modules/cjs/loader.js:583
    throw err;
    ^

Error: Cannot find module 'nan'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:581:15)
    at Function.Module._load (internal/modules/cjs/loader.js:507:25)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:22:18)
    at [eval]:1:1
    at Script.runInThisContext (vm.js:96:20)
    at Object.runInThisContext (vm.js:303:38)
    at Object.<anonymous> ([eval]-wrapper:6:22)
    at Module._compile (internal/modules/cjs/loader.js:689:30)
    at evalScript (internal/bootstrap/node.js:587:27)
gyp: Call to 'node -e "require('nan')"' returned exit status 1 while in binding.gyp. while trying to load binding.gyp
gyp ERR! configure error
gyp ERR! stack Error: `gyp` failed with exit code: 1
gyp ERR! stack     at ChildProcess.onCpExit (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:345:16)
gyp ERR! stack     at ChildProcess.emit (events.js:182:13)
gyp ERR! stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:240:12)
gyp ERR! System Windows_NT 10.0.17134
gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "configure" "--fallback-to-build" "--module=C:\\project\\node_modules\\bcrypt\\lib\\binding\\bcrypt_lib.node" "--module_name=bcrypt_lib" "--module_path=C:\\project\\node_modules\\bcrypt\\lib\\binding" "--napi_version=3" "--node_abi_napi=napi" "--napi_build_version=0" "--node_napi_label=node-v64" "--python=C:\\Users\\xxxxx\\.windows-build-tools\\python27\\python.exe"

EDIT 1
The nan package is def installed. When I run npm list nan, I get:
aconcagua@0.0.0 C:\project
+-- @angular-devkit/build-angular@0.8.9
| `-- node-sass@4.11.0
|   `-- nan@2.12.1  deduped
+-- @angular/compiler-cli@6.1.10
| `-- chokidar@1.7.0
|   `-- UNMET OPTIONAL DEPENDENCY fsevents@1.2.6
|     `-- nan@2.12.1  deduped
`-- nan@2.12.1

I also tried this and added environment variables, with no luck.

A:

The only way I could solve this was resetting windows (10) and starting afresh.  Newish laptop so not too painful. Still, would have been nicer to work out what was wrong and fix it...

