From 1bee9c5442a118b39fb8addeef3884db64ed317b Mon Sep 17 00:00:00 2001
From: = <=>
Date: Sat, 27 Dec 2025 23:04:55 +0530
Subject: [PATCH 1/2] Fix reconstruct: throw ArgumentError on invalid input
 type

---
 docs/src/pca.md | 11 +++++++++++
 src/types.jl    |  8 +++++++-
 test/pca.jl     |  6 ++++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/docs/src/pca.md b/docs/src/pca.md
index 6805e33..d50cf82 100644
--- a/docs/src/pca.md
+++ b/docs/src/pca.md
@@ -117,6 +117,10 @@ predict(::KernelPCA)
 predict(::KernelPCA, ::AbstractVecOrMat{T}) where {T<:Real}
 reconstruct(::KernelPCA, ::AbstractVecOrMat{T}) where {T<:Real}
 size(::KernelPCA)
+```
+!!! note
+	If `reconstruct` is called with an input that is not an `AbstractVecOrMat` of real numbers, an `ArgumentError` is thrown indicating the invalid input type and the expected type.
+```
 projection(::KernelPCA)
 eigvals(::KernelPCA)
 eigvecs(::KernelPCA)
@@ -164,6 +168,10 @@ fit
 size(::PPCA)
 mean(::PPCA)
 var(::PPCA)
+```
+!!! note
+	If `reconstruct` is called with an input that is not an `AbstractVecOrMat` of real numbers, an `ArgumentError` is thrown indicating the invalid input type and the expected type.
+```
 cov(::PPCA)
 projection(::PPCA)
 loadings(::PPCA)
@@ -188,6 +196,9 @@ Here, ``\mathbf{W}`` is the factor loadings or weight matrix.
 predict(::PPCA, ::AbstractVecOrMat{T}) where {T<:Real}
 reconstruct(::PPCA, ::AbstractVecOrMat{T}) where {T<:Real}
 ```
+```
+!!! note
+	If `reconstruct` is called with an input that is not an `AbstractVecOrMat` of real numbers, an `ArgumentError` is thrown indicating the invalid input type and the expected type.
 
 Auxiliary functions:
 
diff --git a/src/types.jl b/src/types.jl
index dbaecb1..012286e 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -23,8 +23,14 @@ projection(model::AbstractDimensionalityReduction) = error("'projection' is not
     reconstruct(model::AbstractDimensionalityReduction, y)
 
 Return the model response (a.k.a. the dependent variable).
+Throws an `ArgumentError` if `y` is not an `AbstractVecOrMat` of real numbers, indicating the invalid 
+input type and the expected type.
 """
-reconstruct(model::AbstractDimensionalityReduction, y) = error("'reconstruct' is not defined for $(typeof(model)).")
+function reconstruct(model::AbstractDimensionalityReduction, y)
+    throw(ArgumentError("Invalid input type $(typeof(y)) for reconstruct(::$(typeof(model))). " * 
+    "Expected an AbstractVecOrMat of real numbers."
+    ))
+end
 
 abstract type LinearDimensionalityReduction <: AbstractDimensionalityReduction end
 
diff --git a/test/pca.jl b/test/pca.jl
index 865b965..4d5bfe5 100644
--- a/test/pca.jl
+++ b/test/pca.jl
@@ -43,6 +43,12 @@ import SparseArrays
     @test reconstruct(M, Y[:,1]) ≈ P * Y[:,1]
     @test reconstruct(M, Y) ≈ P * Y
 
+    @test_throws ArgumentError reconstruct(M, 123)
+    @test_throws ArgumentError reconstruct(M, Dict())
+    @test_throws ArgumentError reconstruct(M, "abc")
+    @test_throws ArgumentError reconstruct(M, 8923.29)
+    @test_throws ArgumentError reconstruct(M, 1+2im)
+
 
     ## PCA with non-zero mean
 

From 62dfcfff5a89a58d5131f0691f720fba76f44c1c Mon Sep 17 00:00:00 2001
From: = <=>
Date: Sun, 28 Dec 2025 00:05:32 +0530
Subject: [PATCH 2/2] Update CI workflow: use actions/cache@v3 to fix
 deprecation error

---
 .github/workflows/ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 644faa5..b85578e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -36,7 +36,7 @@ jobs:
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
-      - uses: actions/cache@v1
+      - uses: actions/cache@v3
         env:
           cache-name: cache-artifacts
         with: